Podcast
Questions and Answers
E. coli does ferment lactose.
E. coli does ferment lactose.
True
What antigen is present on the capsule of E. coli?
What antigen is present on the capsule of E. coli?
K antigen
When E. coli grows on ___ agar, it produces a green sheen.
When E. coli grows on ___ agar, it produces a green sheen.
EMB agar
When E. coli grows on EMB agar, it produces a ___ sheen.
When E. coli grows on EMB agar, it produces a ___ sheen.
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E. coli is catalase negative.
E. coli is catalase negative.
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What virulence factor of E. coli plays a part in urinary tract infections?
What virulence factor of E. coli plays a part in urinary tract infections?
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E. coli is the number one cause of ____.
E. coli is the number one cause of ____.
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E. coli is the leading cause of gram-negative ____.
E. coli is the leading cause of gram-negative ____.
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E. coli's ability to cause sepsis is due to the virulence factor, ___.
E. coli's ability to cause sepsis is due to the virulence factor, ___.
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The K antigen virulence factor causes what disease?
The K antigen virulence factor causes what disease?
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EHEC is commonly transmitted from ____.
EHEC is commonly transmitted from ____.
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EHEC will present with what GI complaint?
EHEC will present with what GI complaint?
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EHEC ___ lactose and ___ sorbitol.
EHEC ___ lactose and ___ sorbitol.
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EHEC's virulence factor is ___. Where does it bind?
EHEC's virulence factor is ___. Where does it bind?
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Shiga-like toxin can cause what disease in children, especially those under 10 years old?
Shiga-like toxin can cause what disease in children, especially those under 10 years old?
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What is the MOA of hemolytic uremic syndrome?
What is the MOA of hemolytic uremic syndrome?
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What serotype is associated with outbreaks?
What serotype is associated with outbreaks?
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ETEC is associated with what disease?
ETEC is associated with what disease?
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ETEC is transmitted via what?
ETEC is transmitted via what?
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What are the ETEC toxins?
What are the ETEC toxins?
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Which of the ETEC toxins is similar to cholera?
Which of the ETEC toxins is similar to cholera?
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The diarrhea caused by ETEC is bloody.
The diarrhea caused by ETEC is bloody.
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Study Notes
Escherichia coli Overview
- E. coli ferments lactose, categorizing it as a lactose fermenter.
- K antigen present on E. coli’s capsule indicates its encapsulated nature.
Culturing E. coli
- E. coli produces a green sheen when cultured on EMB agar.
Biochemical Characteristics
- E. coli is catalase positive, which contributes to its survival in the presence of hydrogen peroxide.
Pathogenicity
- Fimbriae (pili) are a key virulence factor responsible for urinary tract infections.
- E. coli is the most common cause of urinary tract infections and is a leading cause of gram-negative sepsis.
- Lipopolysaccharide (LPS) acts as a virulence factor, enabling E. coli to cause sepsis.
Specific Diseases Caused by E. coli
- The K antigen is implicated in neonatal meningitis.
- EHEC (Enterohemorrhagic E. coli) is typically transmitted through undercooked hamburgers and causes bloody diarrhea.
- EHEC ferments lactose but does not ferment sorbitol, differentiating it from other types.
- Shiga-like toxin is a virulence factor of EHEC, targeting the 60S ribosomal subunit and can lead to hemolytic uremic syndrome, affecting children under 10.
Mechanism of Hemolytic Uremic Syndrome
- Shiga-like toxin damages endothelial cells, leading to platelet aggregation, which fragments passing red blood cells, resulting in schistocytes.
EHEC Serotype
- Serotype O157:H7 is frequently associated with outbreaks of EHEC.
Traveler's Diarrhea and ETEC
- ETEC (Enterotoxigenic E. coli) causes traveler's diarrhea, primarily transmitted through contaminated water.
- ETEC toxins include heat-labile toxin, which increases cAMP, and heat-stabile toxin, which increases cGMP.
- The heat-labile toxin shares similarities with cholera toxin.
Clinical Presentation of ETEC
- Diarrhea caused by ETEC is typically nonbloody and characterized by watery stools.
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Description
This quiz focuses on key characteristics of Escherichia coli, including its ability to ferment lactose and the specifics of its growth on EMB agar. Test your knowledge of its antigens and other defining traits with these flashcards. Perfect for students studying microbiology!
